Photovoltaic (PV) modules are becoming increasingly popular for providing renewable energy. FIGS. 1 and 2 show a top perspective view and a bottom perspective view, respectively, of a conventional photovoltaic module 10. The module 10 may use any photovoltaic technology, including thin film technologies that use cadmium telluride (CdTe) or copper indium gallium diselenide (CIGS) as a semiconductor absorber layer, crystalline silicon technologies, or others.
Module 10 is oriented to receive sunlight through a front layer 110. The sunlight is then converted to electricity using semiconductor materials embedded therein. To properly manage this conversion process, module 10 can be divided into a plurality of PV cells formed between front layer 110 and back plate 140 and arranged across the module. The cells can be connected in series, parallel, or a combination thereof depending on the desired electrical output from module 10.
Front layer 110 is the outermost layer of the module 10, and is also the first layer that incident light encounters upon reaching module 10. Front layer 110 may be composed of a substrate that is both durable and highly transparent, such as, for example, borosilicate glass, soda lime glass, or float glass. Back plate 140 together with front layer 110 encloses module 10 with an edge-insulating seal 245 provided therebetween. Back plate 140 can be composed of any suitable protective material, and is typically formed of a substrate such as borosilicate glass, float glass, soda lime glass, carbon fiber, or polycarbonate. Back plate 140, front layer 110, and insulating seal 245 protect the plurality of layers of module 10 from moisture intrusion, physical damage, or environmental hazards.
As shown in FIG. 2, external conductors 120, 125 facilitate connection and transmission of the electrical current generated by module 10 to other electrical devices or loads. External conductors 120, 125 may be any appropriate electrically conductive wires or cables, and may include insulating jackets surrounding their conductive core. External conductors 120, 125 may include industry-standard connectors 130, 135 for ease of installation and interconnection with other elements in a photovoltaic system. A conductor interface 150, also termed a junction box or cord plate, installed on back plate 140 of module 10 houses the interconnections of positive and negative internal busses of module 10 with respective external conductors 120, 125. Brackets 115 may be connected to module 10 (for example, to peripheral edges of front layer 110 and back plate 140) for use in fixing module 10 to a support structure.
In order to identify and track individual photovoltaic modules 10 during a fabrication process and/or deployment in a solar farm, a unique barcode or other identifying mark may be placed on one of the substrates of the module (e.g., front layer 110 or back plate 140). FIG. 3 shows one example of a barcode 30 that may be placed on the front layer 110 or back plate 140 of module 10. Barcode 30 is a two-dimensional dot matrix bar code. It should be understood, however, that any type of bar code can be used, including any two-dimensional or matrix barcode, such as a stacked barcode involving multiple rows of vertical bars arranged on top of one another, a one-dimensional (also referred to as “linear”) bar code, a human readable barcode, a shape, a graphic, or any other suitable identifying mark which can be used to identify and track individual photovoltaic modules 10 during or after fabrication. In addition to identifying the unique marked module 10, barcode 30 may also identify other characteristics about the marked module 10, such as the manufacturer and manufacturing line, the type of photovoltaic technology that the module 10 employs, and other characteristics.
FIG. 4 shows a portion of a sequential manufacturing process 40 for module 10. Various processing stages 410, 420, 430 of a photovoltaic module manufacturing line are depicted. For example, processing stages 410, 420, 430 may be used to deposit and/or treat various material layers on a substrate during manufacture of module 10. A laser marking process, in which a barcode or other identifying mark is applied to the module using a laser head, can be performed at any stage of the manufacturing process. For example, the laser marking process may be performed at the beginning of a manufacturing line, such as when a substrate, e.g., a starting glass used for the front layer 110 or back plate 140 of FIGS. 1 and 2, first enters the manufacturing line. Alternatively, the laser marking process may be performed at an end location in the manufacturing line, such as when the completed photovoltaic module 10 exits the manufacturing line, or at some location between the various processing stages 410, 420, 430.
In order to maintain throughput of the process 40 with independent marking of the manufactured module 10, a marking device is dedicated to each manufacturing line. Thus, if multiple manufacturing lines are operated concurrently, or if the module formation processes occur faster than the marking process, multiple laser marking devices are required. Operating multiple spaced apart laser marking devices adds additional fixed costs (for multiple marking devices) and operational costs (workers and/or maintenance for each marking device) to the manufacturing process 40.
Alternatively, a single laser marking device may be used to mark modules for multiple manufacturing lines, but this may result in a bottleneck at the marking location.
In addition, in the event that a laser head or lens of the laser marking device requires maintenance or replacement, the laser marking device must be deactivated and the one or more manufacturing lines that it services stopped while the laser head is repaired or replaced. Furthermore, certain lasers, such as CO2 laser heads, utilize gas as an active medium to amplify the light signal, and discharge this gas during normal operation. The lenses of such laser heads require regular maintenance during normal operation, which also requires deactivating the laser head and stopping the manufacturing line.
Accordingly, there is continuing need for an object marking method and apparatus providing greater efficiency in both fixed and operational costs and manufacturing time.